This invention relates to communication switching, and in particular, to the provision of features to a wireless handset as the handset is handed off from switching node to switching node.
Highly distributed switching systems are described in U.S. Pat. Nos. 5,182,751 and 5,377,262. Such distributed systems have an advantage in a wireless telecommunication system in that they are readily expandable at low cost. This is important in a wireless telecommunication system that is being used in the office, industrial, or warehouse environment where initially the system starts out with a minimal number of users and then grows to a large number of users. Such a distributed system consists of a number of switch nodes each of which is an independent switching system. An example of such a distributed system is illustrated in FIG. 1. Each switch node handles a relatively small number of wireless handsets such as a hundred wireless handsets. The manner in which the switch nodes communicate signaling information within the network of switch nodes and route calls is well described in the above-referenced U.S. patents.
The software architecture of the above-referenced U.S. patents was designed with wired telephone sets in mind. Whereas the distributed switch node architecture has been successfully applied to large wireless telecommunication systems there have arisen certain problems. These problems have resulted from the fact that as an individual user proceeds through the area covered by the distributed telecommunication system, they move from switch node to switch node; hence, must be registered on each switch node. This problem has not arisen in cellular switching systems because cells within a cellular system are so large that it is difficult for a user, even traveling at high speeds in an automobile, to move between more than two or three cells in the course of a conversation. However, in a PCS system based on a distributed switch node architecture as illustrated in FIG. 1, it is quite possible for a user who is walking rapidly and receiving multiple calls at a time to be registered on all switch nodes within the PCS system before becoming inactive. The result is that information concerning the user and their calls and any call features that have been invoked must be continuously handed off to the different switch nodes. Because of the distributed nature of the switch nodes, they do not each have an individual communication link to every node within the switch node architecture. This results in large amounts of data being moved during an active call through multiple switch nodes and enhances the possibility of calls being lost or mishandled.
It is clear that problems exist in the existing software architecture for distributed switch nodes in certain PCS system environments.
The foregoing problems are solved, and a technical advance is achieved by an apparatus and method in a distributed wireless telecommunication system. The software architecture of the wireless telecommunication system divides the function of wireless handset control from the function of telecommunication call control. The wireless handset control function follows the wireless handset as it registers and is handed off from switch node to switch node; advantageously, the telecommunication call control function remains on the switch node on which the wireless handset first became active and remains on that switch node until the wireless handset becomes inactive. Upon the wireless handset becoming inactive, the wireless telecommunication call control function is transferred to the switch node on which the wireless handset is currently registered.
Other and further aspects of the present invention will become apparent during the course of the following description and by reference to the accompanying drawing.